Did giraffe cardiovascular evolution solve the problem of heart failure with preserved ejection fraction?

Figures

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  Figure 1.. Evolutionary divergence of the giraffe from the okapi and other mammals. Created using the Interactive Tree of Life [31].

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  Figure 2.. Comparison of the response of the left ventricle of the giraffe to increasing hypertension over the course of development vs. the ventricular response to chronic hypertension in humans. In both cases, hypertension leads to thickening (i.e. hypertrophy) of the left ventricular wall. Hypertension-induced left ventricular thickening (LVT) in humans leads to cardiac pathologies such as fibrosis, and commonly heart failure with preserved ejection fraction (HFpEF). However, developmental pressure-induced LVT in growing giraffes does not compromise exercise capacity, which is an important adaptation this prey species. HFpEF, heart failure with preserved ejection fraction.

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  Figure 3.. Comparison of gross ventricular anatomy in the healthy human adult heart, human heart failure, and healthy adult giraffe hearts and their relationships to left atrial and ventricular pressure. Despite significant pressure-induced left ventricular thickening (LVT), giraffe cardiac pressures do not display the elevated left atrial and ventricular pressures observed in humans with severe hypertension-induced LVT. Giraffe ventricular pressures adapted from Smerup et al. [33]. HFpEF, heart failure with preserved ejection fraction.